It is known to fasten two sheets together using rivets, however these fasteners have their drawbacks in that they leave an unacceptable aesthetic appearance since they do not leave a finish which is flush with the surface of the sheets. It is known to attach two metal sheets with an insert that provides a flush finish as shown in U.S. Pat. No. 3,242,962 issued to Dupree, however the materials with which the Dupree insert may be used are limited to those capable of cold flow deformation when the insert is applied under high pressure. The Dupree fastener can only be installed between the sheets being joined as well. The clinch/broach fastener installs from the top sheet of the two from the outside, permitting the installation of more than one in any array of parts. There is therefore a need in the art for an insert that can join two sheets which are composed of a wide range of different materials while providing joinder of the sheets with a flush final finish.